Field of the Invention
In rail vehicles, inter alia, so-called permanent magnet machines, which can also be referred to as permanent magnet motors, are used to drive the rail vehicle. They are generally supplied with electric energy via a three-phase electric network. The electric network also comprises a power converter in this case, which, in motor operation of the permanent magnet machine, converts a DC voltage, for example, a link circuit voltage, into a desired AC voltage for supplying the permanent magnet machine. The power converter can also, in generator operation of the permanent magnet machine, convert the AC voltage generated by the permanent magnet machine into a DC voltage.
Description of Related Art
Undesired short-circuits can occur in the electric network. They can occur both inside the permanent magnet machine, for example, inside a housing of the machine, or along a phase line for connecting the power converter and the permanent magnet machine. Short-circuits can also occur in the power converter. In the event of short-circuits, so-called electric arcs can also occur, which can result in undesired destruction of components of the rail vehicle.
Monitoring a level of a phase current is known, wherein a short circuit is detected if the level of the phase current exceeds a predetermined threshold value.
If such a short circuit is detected, in general the power converter is electrically disconnected from the permanent magnet machine, for example, by appropriately arranged circuit breakers. At the same time, the rail vehicle is decelerated to a standstill, to prevent a potential feed of the short-circuit.
The technical problem arises of providing a method and a device for monitoring an electric network in a rail vehicle and also a rail vehicle, which enable monitoring of the network even in the disconnected state of the electric machine.